diff --git a/composer.json b/composer.json
index 4acb210..15f3584 100644
--- a/composer.json
+++ b/composer.json
@@ -11,8 +11,8 @@
     ],
     "minimum-stability": "dev",
     "require": {
-        "php": ">=7.4",
-        "guzzlehttp/guzzle": "^7.0",
+        "php": ">=5.6",
+        "guzzlehttp/guzzle": "^6.5.x-dev",
         "starkbank/ecdsa": "0.0.5"
     },
     "autoload": {
diff --git a/src/Client.php b/src/Client.php
index 188f8ca..53a0521 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -5,10 +5,10 @@
 
 class Client extends RequestBuilder
 {
-    private ?string $merchantId;
-    private ?string $merchantName;
-    public string $apiEndpoint = 'https://api.monobank.ua/';
-    private \GuzzleHttp\Client $httpClient;
+    private $merchantId;
+    private $merchantName;
+    public $apiEndpoint = 'https://api.monobank.ua/';
+    private $httpClient;
 
     /**
      * Створює клієнт з ключем для запитів до серверу Mono і отримує дані про мерчант
@@ -16,7 +16,7 @@ class Client extends RequestBuilder
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1details/get Так отримуються деталі мерчанту
      */
-    public function __construct(string $token)
+    public function __construct($token='')
     {
         $this->httpClient = new \GuzzleHttp\Client([
             'base_uri' => $this->apiEndpoint,
@@ -37,21 +37,21 @@ public function __construct(string $token)
                 throw new \Exception('Cannot decode json response from Mono', 500);
             }
         } else {
-            throw new \Exception($data['errorDescription'] ?? 'Unknown error response: ' . $json, $response->getStatusCode());
+            throw new \Exception(isset($data['errorDescription']) ? $data['errorDescription'] : 'Unknown error response: ' . $json, $response->getStatusCode());
         }
     }
 
-    public function getMerchantId(): string
+    public function getMerchantId()
     {
         return $this->merchantId;
     }
 
-    public function getMerchantName(): string
+    public function getMerchantName()
     {
         return $this->merchantName;
     }
 
-    public function getClient():  \GuzzleHttp\Client
+    public function getClient()
     {
         return $this->httpClient;
     }
@@ -63,7 +63,7 @@ public function getClient():  \GuzzleHttp\Client
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @throws \Exception
      */
-    public function getPublicKey(): string
+    public function getPublicKey()
     {
         $response = $this->getClient()->request('GET','/api/merchant/pubkey');
         $data = $this->getDataFromGuzzleResponse($response);
@@ -80,7 +80,7 @@ public function getPublicKey(): string
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @throws \Exception
      */
-    public function getMerchant(): array
+    public function getMerchant()
     {
         $response = $this->getClient()->request('GET','/api/merchant/details');
         return $this->getDataFromGuzzleResponse($response);
diff --git a/src/Payment.php b/src/Payment.php
index 8aabce4..2f383b6 100644
--- a/src/Payment.php
+++ b/src/Payment.php
@@ -6,7 +6,7 @@
 
 class Payment extends RequestBuilder
 {
-    private \MonoPay\Client $client;
+    private $client;
 
     public function __construct(\MonoPay\Client $client)
     {
@@ -20,9 +20,10 @@ public function __construct(\MonoPay\Client $client)
      * @param array $options Додаткові параметри (Див. посилання)
      * @return array
      * @throws \GuzzleHttp\Exception\GuzzleException
+     * @throws \Exception
      * @link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1invoice~1create/post
      */
-    public function create(int $amount, array $options=[]): array
+    public function create( $amount,  $options=[])
     {
         if($amount < 1){
             throw new \Exception('Amount must be a natural number',500);
@@ -43,7 +44,7 @@ public function create(int $amount, array $options=[]): array
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @throws \Exception
      */
-    public function info(string $invoiceId): array
+    public function info($invoiceId)
     {
         $response = $this->client->getClient()->request('GET','/api/merchant/invoice/status',[
             \GuzzleHttp\RequestOptions::QUERY => [
@@ -63,7 +64,7 @@ public function info(string $invoiceId): array
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @throws \Exception
      */
-    public function refund(string $invoiceId, array $options=[]): array
+    public function refund( $invoiceId, array $options=[])
     {
         $options['invoiceId'] = $invoiceId;
 
@@ -78,10 +79,10 @@ public function refund(string $invoiceId, array $options=[]): array
      * Інвалідація рахунку
      * Інвалідація рахунку, якщо за ним ще не було здіснено оплати
      * @param string $invoiceId ID рахунку
+     * @throws \GuzzleHttp\Exception\GuzzleException*@throws \Exception
      * @link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1invoice~1remove/post
-     * @throws \GuzzleHttp\Exception\GuzzleException
      */
-    public  function cancel(string $invoiceId): array
+    public  function cancel($invoiceId)
     {
         $response = $this->client->getClient()->request('POST','/api/merchant/invoice/remove',[
             \GuzzleHttp\RequestOptions::JSON => [
@@ -99,7 +100,7 @@ public  function cancel(string $invoiceId): array
      * @throws \Exception
      *@link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1invoice~1payment-info?invoiceId=%7BinvoiceId%7D/get
      */
-    public function successDetails(string $invoiceId): array
+    public function successDetails($invoiceId)
     {
         $response = $this->client->getClient()->request('GET','/api/merchant/invoice/payment-info',[
             \GuzzleHttp\RequestOptions::QUERY => [
@@ -120,7 +121,7 @@ public function successDetails(string $invoiceId): array
      * @throws \Exception
      * @link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1invoice~1finalize/post
      */
-    public function captureHold(string $invoiceId, int $amount = null): array
+    public function captureHold( $invoiceId,  $amount = null)
     {
         $body = [
             'invoiceId' => $invoiceId
@@ -145,7 +146,7 @@ public function captureHold(string $invoiceId, int $amount = null): array
      * @throws \Exception
      * @link https://api.monobank.ua/docs/acquiring.html#/paths/~1api~1merchant~1statement/get
      */
-    public function items(int $fromTimestamp, int $toTimestamp=null): array
+    public function items( $fromTimestamp,  $toTimestamp=null)
     {
         $query = [
             'from' => $fromTimestamp
@@ -158,7 +159,7 @@ public function items(int $fromTimestamp, int $toTimestamp=null): array
         ]);
 
         $data = $this->getDataFromGuzzleResponse($response);
-        return $data['list']??[];
+        return isset($data['list']) ? $data['list'] : [];
     }
 
 }
\ No newline at end of file
diff --git a/src/RequestBuilder.php b/src/RequestBuilder.php
index 89bcb93..57b9c86 100644
--- a/src/RequestBuilder.php
+++ b/src/RequestBuilder.php
@@ -6,7 +6,7 @@
 
 class RequestBuilder
 {
-    protected function getDataFromGuzzleResponse(\Psr\Http\Message\ResponseInterface $response): array
+    protected function getDataFromGuzzleResponse(\Psr\Http\Message\ResponseInterface $response)
     {
         $json = $response->getBody()->getContents();
         if(!$json){
diff --git a/src/Webhook.php b/src/Webhook.php
index c564b75..99ff33a 100644
--- a/src/Webhook.php
+++ b/src/Webhook.php
@@ -6,8 +6,8 @@
 
 class Webhook
 {
-    private string $publicKeyBase64;
-    private string $xSignBase64;
+    private $publicKeyBase64;
+    private $xSignBase64;
 
     /**
      * Класс для верифікації даних з вебхука
@@ -17,7 +17,7 @@ class Webhook
      * @throws \GuzzleHttp\Exception\GuzzleException
      * @throws \Exception
      */
-    public function __construct(\MonoPay\Client $client, string $publicKeyBase64=null, string $xSignBase64=null)
+    public function __construct(\MonoPay\Client $client,  $publicKeyBase64=null,  $xSignBase64=null)
     {
         if(!$publicKeyBase64){
             $publicKeyBase64 = $client->getPublicKey();
@@ -40,7 +40,7 @@ public function __construct(\MonoPay\Client $client, string $publicKeyBase64=nul
      * @param string|null $requestBody Тіло запиту. Зазвичай це json body вхідного запиту який можна отримати через функцію file_get_contents('php://input')
      * @return bool Чи коректні вхідні дані
      */
-    public function verify(string $requestBody=null): bool
+    public function verify( $requestBody=null)
     {
         if(empty($requestBody)){
             $requestBody = file_get_contents('php://input');